Typically, communication between electronic control units (ECU) within a vehicle has been operated by a controller area network (CAN). However, due to relatively low speed of the CAN communication, it has been actively attempted to use a commercial Ethernet for communication between control units in the vehicle recently.
By using the commercial Ethernet, it may be possible to reduce cost for constructing a system with cheap commercial parts. It is also advantageous to keep wiring and connection structure simple by connecting local networks from ECUs to a main system bus.
If the Ethernet is used as above, a control unit may include a central processing unit (CPU) and a physical layer (PHY) device (e.g. a chip) which is capable of connecting the CPU to an external device. As noted in its abbreviation, the PHY device is directed to a physical layer, i.e., a connecting part of the control unit to the outer system. In particular, the PHY device may have functions incorporating a transceiver function which include receiving external signals, converting them into signals which is readable by CPU, decrypting encoded or modulated data into original packets and transferring such data to CPU.
Such a PHY device can be initiated to operate by receiving a predetermined value necessary for operation from the CPU via serial communication when booting of the CPU is completed. Therefore, while booting of the CPI is in process, the normal operation of PHY device cannot be secured. Meanwhile, several ECUs installed within a vehicle can include various types of CPUs, and their operating system (OS) can be different to each other. Thus, booting time of the CPU in each control unit can be different. With aforementioned reasons, when two or more of ECUs need to communicate through their individual PHY devices for a certain operation, for example, an operation of a rear view camera during which a camera controller unit and a head unit display controller unit work together, the PHY devices may not be able to operate properly because of any certain delay in one of the CPUs' booting and this may cause further delays in such operation.